The death of a woman whose body was found in a river alongside her partner is being treated as suspicious, police said on Monday.

Postmortem tests on the man and woman, both in their 40s and from the Surrey area, found the woman died before entering the water, probably as the result of strangulation. The man died from drowning, Norfolk police said.

Officers had launched a search after finding the woman's daughter, a 13-year-old girl, alone but unharmed on a cruiser on the Norfolk Broads on Saturday. The bodies were found in the river Bure.

Neither body has been formally identified but police said the man's death was not being treated as suspicious.

Further forensic tests will be carried out on the woman's body and could take up to 48 hours

Detective Superintendent Jes Fry, of the joint Norfolk and Suffolk major investigation team, said: "Our concerns remain for the welfare of the 13-year-old girl.

"We are not looking for anyone else in connection with this incident.

"Both deaths will now be referred to the coroner and a file will be prepared for the inquest."